[PATCH] ieee1394: ohci1394: add reg_flush, remove bogus barriers
From: Stefan Richter
Date: Sun Mar 04 2007 - 21:39:52 EST
Add a utility function to flush MMIO writes.
Remove some mb()s which didn't do anything.
There are still a few wmb()s in ohci1394 which look suspicious.
Shouldn't there be dma_sync_*() calls instead?
Signed-off-by: Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>
---
drivers/ieee1394/ohci1394.c | 47 +++++++++---------------------------
drivers/ieee1394/ohci1394.h | 14 ++++++----
2 files changed, 21 insertions(+), 40 deletions(-)
Index: linux/drivers/ieee1394/ohci1394.h
===================================================================
--- linux.orig/drivers/ieee1394/ohci1394.h
+++ linux/drivers/ieee1394/ohci1394.h
@@ -248,17 +248,19 @@ static inline int cross_bound(unsigned l
return 0;
}
-/*
- * Register read and write helper functions.
- */
+/* Register read and write helper functions */
static inline void reg_write(const struct ti_ohci *ohci, int offset, u32 data)
{
- writel(data, ohci->registers + offset);
+ writel(data, ohci->registers + offset);
}
-
static inline u32 reg_read(const struct ti_ohci *ohci, int offset)
{
- return readl(ohci->registers + offset);
+ return readl(ohci->registers + offset);
+}
+/* A dummy read to force all PCI writes to be posted immediately */
+static inline void reg_flush(const struct ti_ohci *ohci)
+{
+ readl(ohci->registers);
}
Index: linux/drivers/ieee1394/ohci1394.c
===================================================================
--- linux.orig/drivers/ieee1394/ohci1394.c
+++ linux/drivers/ieee1394/ohci1394.c
@@ -1438,12 +1438,8 @@ static void ohci_iso_recv_change_channel
reg = listen ? OHCI1394_IRMultiChanMaskHiSet : OHCI1394_IRMultiChanMaskHiClear;
i = channel - 32;
}
-
reg_write(recv->ohci, reg, (1 << i));
-
- /* issue a dummy read to force all PCI writes to be posted immediately */
- mb();
- reg_read(recv->ohci, OHCI1394_IsochronousCycleTimer);
+ reg_flush(recv->ohci);
}
static void ohci_iso_recv_set_channel_mask(struct hpsb_iso *iso, u64 mask)
@@ -1464,10 +1460,7 @@ static void ohci_iso_recv_set_channel_ma
reg_write(recv->ohci, OHCI1394_IRMultiChanMaskHiClear, (1 << (i-32)));
}
}
-
- /* issue a dummy read to force all PCI writes to be posted immediately */
- mb();
- reg_read(recv->ohci, OHCI1394_IsochronousCycleTimer);
+ reg_flush(recv->ohci);
}
static int ohci_iso_recv_start(struct hpsb_iso *iso, int cycle, int tag_mask, int sync)
@@ -1477,7 +1470,6 @@ static int ohci_iso_recv_start(struct hp
u32 command, contextMatch;
reg_write(recv->ohci, recv->ContextControlClear, 0xFFFFFFFF);
- wmb();
/* always keep ISO headers */
command = (1 << 30);
@@ -1521,7 +1513,7 @@ static int ohci_iso_recv_start(struct hp
if (sync != -1) {
/* set sync flag on first DMA descriptor */
- struct dma_cmd *cmd = &recv->block[recv->block_dma];
+ struct dma_cmd *cmd = &recv->block[recv->block_dma];
cmd->control |= cpu_to_le32(DMA_CTL_WAIT);
/* match sync field */
@@ -1545,11 +1537,6 @@ static int ohci_iso_recv_start(struct hp
/* run */
reg_write(recv->ohci, recv->ContextControlSet, 0x8000);
- /* issue a dummy read of the cycle timer register to force
- all PCI writes to be posted immediately */
- mb();
- reg_read(recv->ohci, OHCI1394_IsochronousCycleTimer);
-
/* check RUN */
if (!(reg_read(recv->ohci, recv->ContextControlSet) & 0x8000)) {
PRINT(KERN_ERR,
@@ -2116,13 +2103,8 @@ static int ohci_iso_xmit_queue(struct hp
wmb();
/* wake DMA in case it is sleeping */
- reg_write(xmit->ohci, xmit->ContextControlSet, 1 << 12);
-
- /* issue a dummy read of the cycle timer to force all PCI
- writes to be posted immediately */
- mb();
- reg_read(xmit->ohci, OHCI1394_IsochronousCycleTimer);
-
+ reg_write(ohci, xmit->ContextControlSet, 1 << 12);
+ reg_flush(ohci);
return 0;
}
@@ -2132,11 +2114,10 @@ static int ohci_iso_xmit_start(struct hp
struct ti_ohci *ohci = xmit->ohci;
/* clear out the control register */
- reg_write(xmit->ohci, xmit->ContextControlClear, 0xFFFFFFFF);
- wmb();
+ reg_write(ohci, xmit->ContextControlClear, 0xFFFFFFFF);
/* address and length of first descriptor block (Z=3) */
- reg_write(xmit->ohci, xmit->CommandPtr,
+ reg_write(ohci, xmit->CommandPtr,
dma_prog_region_offset_to_bus(&xmit->prog, iso->pkt_dma * sizeof(struct iso_xmit_cmd)) | 3);
/* cycle match */
@@ -2145,28 +2126,28 @@ static int ohci_iso_xmit_start(struct hp
/* 'cycle' is only mod 8000, but we also need two 'seconds' bits -
just snarf them from the current time */
- u32 seconds = reg_read(xmit->ohci, OHCI1394_IsochronousCycleTimer) >> 25;
+ u32 seconds = reg_read(ohci, OHCI1394_IsochronousCycleTimer) >> 25;
/* advance one second to give some extra time for DMA to start */
seconds += 1;
start |= (seconds & 3) << 13;
- reg_write(xmit->ohci, xmit->ContextControlSet, 0x80000000 | (start << 16));
+ reg_write(ohci, xmit->ContextControlSet, 0x80000000 | (start << 16));
}
/* enable interrupts */
- reg_write(xmit->ohci, OHCI1394_IsoXmitIntMaskSet, 1 << xmit->task.context);
+ reg_write(ohci, OHCI1394_IsoXmitIntMaskSet, 1 << xmit->task.context);
/* run */
- reg_write(xmit->ohci, xmit->ContextControlSet, 0x8000);
- mb();
+ reg_write(ohci, xmit->ContextControlSet, 0x8000);
+ reg_flush(ohci);
/* wait 100 usec to give the card time to go active */
udelay(100);
/* check the RUN bit */
- if (!(reg_read(xmit->ohci, xmit->ContextControlSet) & 0x8000)) {
+ if (!(reg_read(ohci, xmit->ContextControlSet) & 0x8000)) {
PRINT(KERN_ERR, "Error starting IT DMA (ContextControl 0x%08x)\n",
reg_read(xmit->ohci, xmit->ContextControlSet));
return -1;
@@ -3674,8 +3655,6 @@ int ohci1394_stop_context(struct ti_ohci
"Runaway loop while stopping context: %s...", msg ? msg : "");
return 1;
}
-
- mb();
udelay(10);
}
if (msg) PRINT(KERN_ERR, "%s: dma prg stopped", msg);
--
Stefan Richter
-=====-=-=== --== --=-=
http://arcgraph.de/sr/
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/